ios - Swift Realm - 如何计算单列中的所有数据？

Question

这是我的类(class)的样子:

class Card : Object {
    @objc dynamic var tags: String = ""
    @objc dynamic var set_id: String = ""
}

我想从所有带有转发的set_id的卡片中返回标签的数量。
方法如下:

func totalTags() -> String {
        var tagCounter: Int = 0
        let realm = try? Realm()
        let totalCards = realm!.objects(Card.self).filter("set_id = '\(setId)'") //all Cards with selected set_id, set_id is global var.
        for card in 0...totalCards.count {
            //every 'card' has tags, but there there can me more tags,
            //like : tags="one,twitter,world,Europe"...
            //And I want to count all of them for every 'card'
            let result = realm.objects(Card.self).filter() //How to filter?
            tagCounter += //what? result.count or something?
        }
        return String(tagCounter)
    }

Answer 1

我知道 tags: String 包含逗号分隔的元素，并且您想要查找元素的数量。

您可以通过迭代totalCards来做到这一点。对于每张卡片，将标签拆分为一个数组并计算元素数量。

for card in totalCards {
    tagCounter += card.tags.components(separatedBy: ",").count
}

组件(separatedBy:) documentation